It's in the title.
'''
machine-upgrades/script/module-counter.lua:32: Positive and negative modules for this category (quality) were supposed to have equal magnitude in effect, but opposite sign! {
"[LuaItemPrototype: mupgrade-module-quality (module)]",
"[LuaItemPrototype: mupgrade-module-quality-negative (module)]"
}
stack traceback:
[C]: in function 'assert'
machine-upgrades/script/module-counter.lua:32: in main chunk
[C]: in function 'require'
machine-upgrades/script/technology-linker.lua:3: in main chunk
[C]: in function 'require'
machine-upgrades/control.lua:6: in main chunk
''''

Thanks for the report. Sorry to hear this is happenning to you.

It looks like you installed a mod that changes the values of quality modules programmatically. This is an incompatibility issue caused from another mod failing to mind its own damn business. I recommend looking through your mods for one that messes with quality modules. Let me know which one. I may be able to upload a quick fix to change the execution order to stop that mod from messing with my mod's internal data.

If you are struggling to find it, I can send you a dev build that can print more information.

Alright got a list;
[✓]https://mods.factorio.com/mod/adjustable-quality
[Unchecked]https://mods.factorio.com/mod/customizable-quality-names
[Unchecked]https://mods.factorio.com/mod/QualityAssurance
[Unchecked]https://mods.factorio.com/mod/SteeperQuality
Tbh I might yeet a few of these but for testing reasons, I can try to narrow it down with a few relaunches.

Edit: Worked when adjustable-quality was removed.

I remember now why I added that mod, it helped tame the quality demons... / nerf quality.

It is fixed. Please upgrade to the newest version of Machine Upgrades.